afv-library/skills/creating-sf-skill/examples/simple-metadata-skill/SKILL.md

name	description	metadata
generating-validation-rule	Create and update Salesforce validation rules for any standard or custom object. Use when the user asks to add a validation rule, enforce field requirements, prevent invalid data entry, or implement record-level business logic constraints. TRIGGER when: user says validation rule, field validation, required field check, data constraint, record validation, prevent invalid data. DO NOT TRIGGER when: user asks about Flow validation or Apex validation logic — delegate to generating-flow or generating-apex.	version stage license 1.0 Draft LICENSE.txt has complete terms

Generating Validation Rules

Create validation rules that enforce business logic at the record level.

Scope

• In scope: Creating new validation rules, updating existing rules, formula syntax, error message placement, activation/deactivation.
• Out of scope: Flow-based validation (use generating-flow), Apex triggers for complex validation (use generating-apex).

Required Inputs

• Target object (standard or custom)
• Business rule to enforce (in plain language)
• Error message text
• Error location (top of page or specific field)

Defaults:

• Active: true
• Description: auto-generated from the business rule

Workflow

1. Identify the object — confirm the API name of the target object.
2. Understand the rule — translate the business requirement into a boolean formula.
3. Check existing rules — look for overlapping validation rules on the same object.
4. Read the metadata template — load ./assets/validation_rule_template.xml before generating.
5. Write the formula — the formula must evaluate to TRUE when the data is invalid. For common formula patterns, read ./references/formula_patterns.md.
6. Set error message — clear, user-friendly message explaining what's wrong and how to fix it.
7. Create metadata file — generate the .validationRule-meta.xml using the template structure. Compare against ./examples/require_email_on_contact.xml for expected output format.
8. Syntax check — verify the formula compiles (field API names, function syntax).
9. Edge case review — test with null values, blank strings, boundary conditions.

Rules

Constraint	Rationale
Formula evaluates to TRUE on invalid data	Salesforce convention — TRUE = error
Use API names, not labels	Labels change; API names are stable
Handle null fields with ISBLANK()	Prevent null pointer errors
Use PRIORVALUE() only in update context	Not available on insert

Gotchas

Issue	Resolution
Rule fires on record types it shouldn't	Add RecordType.DeveloperName check to formula
Rule blocks data migration/bulk loads	Add bypass via Custom Permission or Custom Metadata
ISCHANGED() always false on insert	Guard with NOT(ISNEW()) before using ISCHANGED()
Formula too long (> 5000 chars)	Split into multiple rules or use a helper formula field
Error on wrong field	Verify field API name in errorConditionFormula attribute

Output Expectations

Deliverables per validation rule:

• <ObjectName>.validationRule-meta.xml

File structure follows the template in ./assets/validation_rule_template.xml.

Cross-Skill Integration

Need	Delegate to
Complex multi-object validation	generating-apex (trigger-based)
Flow-based validation with user prompts	generating-flow
Custom object creation	generating-custom-object
Field creation for formula references	generating-custom-field

Reference File Index

File	When to read
./assets/validation_rule_template.xml	Before generating any validation rule metadata file
./references/formula_patterns.md	When writing the formula — common patterns and functions
./examples/require_email_on_contact.xml	To verify generated output matches expected format